Long distance, top secret messages

Oct 19, 2010

When the military needs to send the key to encrypted data across the world, it can't necessarily rely on today's communication lines, where the message could be covertly intercepted. But physicists at the Georgia Institute of Technology in Atlanta are developing a new, more secure way to send such information across far distances, using existing cables and the laws of quantum mechanics.

Alex Kuzmich and colleagues have built a critical component of a quantum repeater, a device that allows -- such as the encryption keys used to encode data transmitted over traditional lines -- to be relayed over larger distances. They will describe this device at the Optical Society's (OSA) 94th annual meeting, Frontiers in Optics (FiO) 2010, at the Rochester Riverside Convention Center in Rochester, N.Y., from Oct. 24-28.

is an emerging technology currently used by both military and financial organizations to send information as entangled particles of light. In theory, anyone who tries to tap into this information changes it in a way that reveals their presence.

A quantum repeater is similar to a transformer on a traditional power line. Instead of converting electricity, it regenerates a communication signal to prevent it from degrading over distance. It contains two banks of memory, one to receive an entangled message and a second line to copy it.

Previously, the longest distance over which an encrypted key could be sent was approximately 100 kilometers. The new technology developed by the Georgia Tech team increases 30-fold the amount of time the memory can hold information, which means that series of these devices -- arrayed like Christmas lights on a string -- could reach distances in excess of 1,000 kilometers.

"This is another significant step toward improving systems based on . For quantum repeaters, most of the basic steps have now been made, but achieving the final benchmarks required for an operating system will require intensive optical engineering efforts," says Kuzmich.

Their device also converts the photons used in quantum devices from an infrared wavelength of 795 nm to a wavelength of 1,367 nm. This wavelength is used in traditional telecommunications lines, so the new device could someday plug into existing fiber optic cables.

"In order to preserve the quantum entanglement, we perform conversion at very high efficiency and with low noise," says Alexander Radnaev, who also works on this project at Georgia Tech.

Explore further: MRI for a quantum simulation

More information: The talk, "Quantum Correlations Between Telecom Light and Memory" is at 9:15 a.m. on Wednesday, Oct. 27.

Related Stories

World Cup Security Uses Physics To Thwart Hackers

Jun 21, 2010

South African physicists working to protect data networks at the World Cup hope to provide something that no goalkeeper can promise: perfect defense. They're tapping the laws of physics to prevent hackers ...

Quantum electronics: Two photons and chips

Jan 20, 2006

Scientists at Toshiba Research Europe Limited (Cambridge, UK) believe they are on to a way of producing entangled twins of photons using a simple semiconductor electronic device. Such a chip-based source of entangled photons ...

Recommended for you

Study finds physical link to strange electronic behavior

16 minutes ago

Scientists have new clues this week about one of the baffling electronic properties of the iron-based high-temperature superconductor barium iron nickel arsenide. A Rice University-led team of U.S., German ...

Refocusing research into high-temperature superconductors

12 hours ago

Below a specific transition temperature superconductors transmit electrical current nearly loss-free. For the best of the so-called high-temperature superconductors, this temperature lies around -180 °C – a temperature ...

MRI for a quantum simulation

18 hours ago

Magnetic resonance imaging (MRI), which is the medical application of nuclear magnetic resonance spectroscopy, is a powerful diagnostic tool. MRI works by resonantly exciting hydrogen atoms and measuring ...

50-foot-wide Muon g-2 electromagnet installed at Fermilab

18 hours ago

One year ago, the 50-foot-wide Muon g-2 electromagnet arrived at the U.S. Department of Energy's Fermi National Accelerator Laboratory in Illinois after traveling 3,200 miles over land and sea from Long Island, ...

User comments : 0